I am guess you can add more ram as it is just a dell hardware platform with a customised red hat.
Not sure it will be offically "supported" by Symantec though...actually pretty sure it wont be at all.
I would just do a backup and restore to a VMware SBG and then try out the new ram.
If it all goes to hell point the mail at your VM SBG....however if it all goes nicely you win.
If I can get my hands on an 82xx I will try it out and let you know.
Let us know how it goes.
Z